A table being just a collection of cells, it's natural to build one from them. The first
example is achieved in the most basic way possible: simple framed cells, all of the same size
and left aligned. The result is rudimentary but very quick to obtain.

The second table brings some improvements: each column has its own width, headings are centered,
and numbers right aligned. Moreover, horizontal lines have been removed. This is done by means
of the border parameter of the Cell() method, which specifies which sides of the
cell must be drawn. Here we want the left (L) and right (R) ones. It remains
the problem of the horizontal line to finish the table. There are two possibilities: either
check for the last line in the loop, in which case we use LRB for the border
parameter; or, as done here, add the line once the loop is over.

The third table is similar to the second one but uses colors. Fill, text and line colors are
simply specified. Alternate coloring for rows is obtained by using alternatively transparent
and filled cells.